GB2442039A

GB2442039A - Telecommunication Security Device

Info

Publication number: GB2442039A
Application number: GB0618767A
Authority: GB
Inventors: Nicholas Hondroyiannis
Original assignee: Individual
Current assignee: Individual
Priority date: 2006-09-22
Filing date: 2006-09-22
Publication date: 2008-03-26
Also published as: GB0618767D0

Abstract

A telecommunication security device 10 has a first input connectable to a first telecommunication device such as a modern capable of dialing up a telephone number. An output of the device is connected to a telecommunication line. The device comprises a switch 14 for enabling and disabling connection between the first input and output, and the switch is controlled by a processor 12 which compares a dialed signal representative of a dialed phone number with a predetermined dial signal. The processor controls the switch on the basis of the comparison. The present invention has a decoder 11 for decoding the signal received from a modem. A processor 12 is arranged to receive the decoded number from the decoder 11 and compare this number with a predetermined number stored in memory. A switching arrangement 14 is arranged to either enable or disable a call to be put through to the PSTN (Public Switched Telephone Network) as is in the normally closed position such that calls can be initiated. Only when a signal is received form the processor will a call be disconnected.

Description

I

Telecommunications Security Device The present invention relates to telecommunications security and particularly to a device for controlling outgoing calls by a telecommunication device such as a modem.

Systems are known for controlling the use of telephone equipment by having phone barring capabilities built into the telephone equipment. This is controlled by software which can receive and store numbers which are allowed to be called and barring any other numbers.

However a problem exists especially with regard to dial-up networking services for internet connection where a modem is adapted to connect to an internet service using a prescribed dial-up number. It is possible for the software controlling the dial-up process to be modified without authorisation from the user such that a different number is dialled. Such a number may be a premium rate number creating extra expense to the user.

To address this problem, the present invention provides a telecommunication security device with a first input connectable to a telecommunication device such as a analogue modem and a first output which is connectable to a telecommunication line, the security device comprising a switching means for enabling and disabling connection between the first input and output, the switching means being controlled by a processor configured to compare a dialled signal indicative of a dialled phone number received from the input with a predetermined dial signal stored in a programmable memoly, wherein the processor controls the switching means on the basis of the result of the comparison.

In order that the present invention is more readily understood, an embodiment will be described by way of example with reference to the accompanying drawing in which: Fig. I shows a schematic diagram of a preferred embodiment of the present invention.

Fig. 2 shows a circuit diagram of the embodiment in Fig. 1.

A preferred embodiment will be described with reference to Fig I which is a schematic diagram showing the overall functionality of the invention.

A security device 10 according to the preferred embodiment is used with an analogue modem I which dials a call and the call is made through a public switched telephone network (PSTN) 2. The security device 10 is in the form of a unit 10 which is provided with a housing (not shown). The unit 10 has a first input port IN1 which is connectable to the modem I through the use of a cable such as a standard RJ 11 cable. A first output port OUT I is provided which is connectable to a telephone line which forms part of the PSTN 2.

The unit 10 comprises a decoder 11 for decoding the signal received from the modem I such that it can be discerned as a phone number. The decoder 11 is capable of handling pulse or tone dialling such that either type of signal can be decoded to the phone number intended to be called by the modem 1.

A processor 12 is arranged to receive the decoded number from the decoder 11 and compare this number with a predetermined number which is stored in memory 13. A switching arrangement 14 is arranged to either enable or disable a call to be put through to the PSTN 2 and is in the normally closed position such that calls can be initiated. Only when a signal is received from the processor 12 will a call be disconnected. The processor 12 can be configured such that if the number received from the decoder 11 is the same as one or more predetermined numbers stored in the memory 13, the switching arrangement is allowed to remain in the closed position enabling a call to be connected. Alternatively if the number received is different to all predetermined numbers stored in the memory 13, the switching arrangement will open and disconnect the call therefore blocking unauthorised numbers.

The unit 10 is a low power device and can use line power from the PSTN 2 in order to power the unit 10. This is achieved by providing an energy store 15 which can be charged from the PSTN 2 whilst the modem I is in an idle state (on-hook). The amount of current drawn from the PSTN 2 whilst the modem I is on-hook is defined by national standards.

The memory 13 is programmable and thus the numbers stored therein can be updated. A manually operable means such as a push button 16 is provided on the housing of the unit 10 allowing it to be pressed by the user. The button 16 is connected to the processor 12 and configured such that when the button 16 is pressed and held during whilst a phone number via input port INI is received by the processor 12 from the decoder 11 and is stored in the memory 13 upon the button release. Thus when a number is dialled by the modem 1, it can be stored in the memory 13 by activating the button. The button 16 therefore places the device into a programming mode. Instead of relying on the modem 1, a telephone (not shown) may replace the modem I and the number can be dialled from the telephone in order to program the memory 13. This obviates the need to use a computer which contains the modem 1 to dial up each number to carry out the programming of the memory 13. It will be appreciated that any type of manually operable means can be used to enable a phone number to be programmed into the memory 13 whilst a number is being dialled. Alternatively whilst the button 16 is activated when in the programming mode i.e. button 16 pressed and held, a predetermined code can be entered via input port IN1, and the device can carry out one or more actions depending on the code entered. For example the entry of a first code can cause the deletion of all the numbers stored in the memory 13. A second code can be used to allow multiple numbers entered via input port INI into memory 13 without the need of the button 16 being activated for each number. This puts the device into a code programming mode.

Furthermore, while programming multiple numbers via input port INI, a symbol typically found on a telephone, for example "#", could be recognised by the device as having a certain meaning such as a confirmation of the end of a number. The pressing of this symbol on a telephone or modem whilst the device is in the code programming mode indicates that the current phone number is complete and can be stored in the memory 13. For security reasons while the device is in code programming mode, it will allow no calls to connect between INI and OUT1. Only when a signout code (e.g. "*14*") is entered whilst the button 16 pressed and held and upon release, the device will return to its normal working mode. In effect there are two programming modes the normal and the code programming mode.

An indicator 17 which is in the form of an LED is arranged on the housing of the unit 10 to provide an indication that the memory 13 is being programmed or the device is in code programming mode. Thus when the button 16 is pressed, this also causes the indicator 17 to be activated.

A preferred embodiment of a circuit which carries out the functionality described above will now be described with reference to Fig. 2.

The decoder 11 of Fig. 1 is shown as DTMF decoder 11 a,Voltage Limiter II b, capacitor C3,C4, resistor R3,R4. The CPU 12 and memory 3 of Fig. I are embodied by component 125. The switching arrangement 14 of Fig I is shown as switches SW1, SW3, and SW4, and inductors LI A, LI B. The energy store 15 is shown as capacitors Cl,C2, bridge rectifier DBRI, resistor RI,R2, diode D1,D2, switch SW2 and voltage regulator 150 and diode 03 is the enable feed for the regulator 150. The push button 16 is shown as switch SW5. The indicator 17 is shown as lamp 17.

When the MODEM I is in the idle state (on-hook), the unit 10 charges it's internal energy store (C1+C2) from the PSTN 2 via the bridge rectifier DBR1 and series network of Ri and Dl. The amount of current drawn from the PSTN 2 in this state is defined by national standards.

When the MODEM I takes the line (off-hook) in preparation to commence a call, the current flowing through LI causes SW1 to close. This enables the voltage regulator 150 to activate and the CPU 125 becomes active. The CPU 125 closes SW2 for a predetermined period of 1-second in order to boost the charge to the internal energy store (C1+C2).

The CPU 125 also activates the DTMF decoder 11 a and waits for either DTMF dialling digits to be received, or for pulse-dialling interruptions to be detected via the voltage limiter lib.

In either case, or combination of both, the number dialled is determined by the CPU 125 and compared to a predetermined number(s) programmed in the on-chip non-volatile memory 125.

If the number is identical to that programmed, the CPU 125 places itself and the DTMF decoder 11 a into a super low-power state awaiting the next call commencement. Therefore the call is allowed through between input port 1NI arid OUT I. If the number is different to that programmed, the CPU 125 closes switch SW3 for a predetermined period of 2-seconds thereby energising switch SW4 to disconnect the MODEM I from the PSTN 2 and cancel the call.

It will be appreciated that the circuit may be adapted to close switch SW3 if the number is the same to that programmed on the on-chip non-volatile memory 125. Accordingly, a list of premium rate numbers which the user does not wish to be dialled could be stored in the memory instead of numbers which the user authorises to be dialled. This effectively will reverse the basic functionality of the device.

Further, the modem I could be replaced by a telephone enabling a telephone call barring service to be set up using the unit 10.

Claims

Claims 1. A telecommunication security device with a first input

connectable to a first telecommunication device capable of dialling up a telephone number and an output which is connectable to a telecommunication line, the security device comprising a switching means for enabling and disabling connection between the first input and the output, the switching means being controlled by a processor arranged to compare a dialled signal representative of a dialled phone number received from the input with a predetermined dial signal stored in a programmable memory, wherein the processor controls the switching means on the basis of the result of the comparison.
2. The security device according to claim 1 further comprising an energy storing means for storing power received from the telecommunication line via the output in order to power the security device.
3. The security device according to claim I or 2 further comprising a manually operable means electrically connected to the processor, whereby in use activation of the manually operable means causes the dialled signal to be stored in the memory.
4. The security device according to claim 3 wherein the manually operable means is a push button switch.
5. The security device according to claim 3 or 4 further comprising a visual indicator for indicating when the manually operable means is activated.
6. The security device according to any preceding claim wherein the processor causes the switching means to connect the first input and the output when the dialled signal representative of a dialled phone number is the same as the predetermined dial signal.
7. The security device according to any one of claims I to 5 wherein the processor causes the switching means to disconnect the first input and the output when the dialled signal representative of a dialled phone number is different to the predetermined dial signal.
8. The security device according to any preceding claim wherein the processor comprises a decoder capable of decoding a dialled signal received from the input into a signal recognisab]e by the processor
9. The security device according to claim 8, wherein the dialled signal is in the form of pulse dialled interruptions.
10. The security device according to claim 8, wherein the dialled signal is in the form of DTMF dialled digits.
11. The security device according to any preceding claim wherein the first telecommunication device is a modem of a computer.
12. The security device according to any preceding claim wherein the first telecommunication device is a telephone.
13. The security device substantially as hereinbefore described with reference to the accompany drawings.